Why is back back button unresponsive but will light up?

I repaired my S7 and when I plugged the screen in to test it out the back button was working perfectly fine and my menu button wouldnt light up but was responsive so I unplugged it, made sure everything was plugged in, and plugged it back in. After that, the menu button was responsive and lighting up but my home button was not responsive but was lighting up. I tried unplugging everything again and plugging it back in but it still didnt work. I then soft reset it and factory reset it but still nothing. Its just weird to me that the light works but its unresponsive. Any ideas?